Conductive structures and assemblies having vertically-stacked memory cells over conductive structures

1. A conductive structure of an integrated circuit, comprising:

an upper primary portion; the upper primary portion comprising a first conductive constituent configured as a container having a bottom and having a pair of sidewalls extending upwardly from the bottom; an interior region of the container being over the bottom and being between the sidewalls; the upper primary portion comprising a second conductive constituent configured as a mass filling the interior region of the container; the second conductive constituent comprising a different composition than the first conductive constituent; the second conductive constituent joining to the first conductive constituent along an interface that extends along interior surfaces of the sidewalls of the container and across an upper surface of the bottom of the container; and

one or more conductive projections joined to the upper primary portion and extending downwardly from the upper primary portion.

2. The conductive structure of claim 1 comprising a planarized upper surface extending across upper surfaces of the first and second conductive constituents.

3. The conductive structure of claim 1 wherein at least one of the one or more conductive projections joins to the upper primary portion at an interconnecting region having substantially sharp corners along a cross-section through the interconnecting region.

4. The conductive structure of claim 1 wherein at least one of the one or more conductive projections joins to the upper primary portion at an interconnecting region having arcuate corners along a cross-section through the interconnecting region.

5. The conductive structure of claim 1 wherein the first conductive constituent comprises metal, and wherein the second conductive constituent comprises conductively-doped semiconductor material.

6. The conductive structure of claim 5 wherein the first conductive constituent comprises a first material, a second material over the first material, and a third material over the second material; wherein the first and third materials comprise a first metal; wherein the second material comprises a second metal different from the first metal; and wherein the second conductive constituent comprises conductively-doped silicon.

7. The conductive structure of claim 6 wherein the first and third materials comprise titanium nitride, and wherein the second material comprises tungsten.

8. The conductive structure of claim 6 wherein at least one of the one or more conductive projections comprises the first, second and third materials.

9. The conductive structure of claim 6 wherein at least one of the one or more conductive projections comprises only the first material.

10. The conductive structure of claim 6 wherein at least one of the one or more conductive projections comprises only the first and second materials.

11. An assembly comprising:

channel material pillars which extend vertically;

memory cells along the channel material pillars;

a conductive structure under the channel material pillars;

the conductive structure comprising an upper primary portion and one or more conductive projections joined to the upper primary portion and extending downwardly from the upper primary portion;

the upper primary portion comprising a first conductive constituent and a second conductive constituent;

the first conductive constituent being configured as a container having a bottom, and having a pair of sidewalls extending upwardly from the bottom;

an interior region of the container being over the bottom and between the sidewalls;

the second conductive constituent being configured as a mass filling the interior region of the container;

the second conductive constituent comprising a different composition than the first conductive constituent;

the second conductive constituent comprising conductively-doped semiconductor material; and

the channel material pillars being directly against the conductively-doped semiconductor material of the second conductive constituent.

12. The assembly of claim 11 wherein the memory cells are NAND memory cells of a NAND memory array.

13. The assembly of claim 11 wherein at least one of the one or more conductive projections joins to the upper primary portion at an interconnecting region having substantially sharp corners along a cross-section through the interconnecting region.

14. The assembly of claim 11 wherein at least one of the one or more conductive projections joins to the upper primary portion at an interconnecting region having arcuate corners along a cross-section through the interconnecting region.

15. The assembly of claim 11 wherein the first conductive constituent comprises metal.

16. The assembly of claim 11 wherein the first conductive constituent comprises a first material, a second material over the first material, and a third material over the second material; wherein the first and third materials comprise a first metal; wherein the second material comprises a second metal different from the first metal; and wherein the second conductive constituent comprises conductively-doped silicon.

17. The assembly of claim 16 wherein the first and third materials comprise titanium nitride, and wherein the second material comprises tungsten.

18. The assembly of claim 16 wherein at least one of the one or more conductive projections comprises the first, second and third materials.

19. The assembly of claim 16 wherein at least one of the one or more conductive projections comprises only the first material.

20. The assembly of claim 16 wherein at least one of the one or more conductive projections comprises only the first and second materials.